Transform-based audio codecs generally introduce inter-harmonic noise when processing harmonic audio signals, particularly at low bitrates.
This effect is further worsen when the transform-based audio codec operates at low delay, due to the worse frequency resolution and/or selectivity introduced by a shorter transform size and/or a worse window frequency response.
This inter-harmonic noise is generally perceived as a very annoying artifact, significantly reducing the performance of the transform-based audio codec when subjectively evaluated on highly tonal audio material.
Several solutions exist to improve the subjective quality of transform-based audio codecs on harmonics audio signals. All of them are based on prediction-based techniques, either in the transform-domain or in the time-domain.
Examples of transform-domain approaches are:                [1] H. Fuchs, “Improving MPEG Audio Coding by Backward Adaptive Linear Stereo Prediction”, 99th AES Convention, New York 1995, Preprint 4086.        [2] L. Yin, M. Suonio, M. Väänänen, “A New Backward Predictor for MPEG Audio Coding”, 103rd AES Convention, New York 1997, Preprint 4521        [3] Juha Ojanperä, Mauri Väänänen, Lin Yin, “Long Term Predictor for Transform Domain Perceptual Audio Coding”, 107th AES Convention, New York 1999, Preprint 5036.        
Examples of time-domain approaches are:                [4] Philip J. Wilson, Harprit Chhatwal, “Adaptive transform coder having long term predictor”, U.S. Pat. No. 5,012,517, Apr. 30, 1991.        [5] Jeongook Song, Chang-Heon Lee, Hyen-O Oh, Hong-Goo Kang, “Harmonic Enhancement in Low Bitrate Audio Coding Using and Efficient Long-Term Predictor”, EURASIP Journal on Advances in Signal Processing 2010.        [6] Juin-Hwey Chen, “Pitch-based pre-filtering and post-filtering for compression of audio signals”, U.S. Pat. No. 8,738,385, May 27, 2014.        